1. Field of the Invention
The present invention concerns an improved free-cutting steel and process for producing.
2. State of the Art
In the production of a low carbon sulfur free-cutting steel called "ultra free-cutting steel", the general practice has been to increase the oxygen content of the steel so that the shape of the sulfide inclusion particles may be spheroidal. On the other hand, a higher oxygen content causes a large amount of oxide inclusion, which increases surface defects of the steel, resulting in lowered strength and poor appearance. If the oxygen content is reduced by using a deoxidizing agent, the sulfide inclusion particles become elongated, and machinability decreases.